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Paleoenvironmental Interpretations Based on Vertebrate Fossil Assemblages: An Example of their Utilization in the Gulf Coast

G. L. Stringer1 and M. M. Miller2
1Department of Geosciences, The University of Louisiana at Monroe, Monroe, LA
2Petroleum Automation Consultants, Inc., Monroe, LA

Several invertebrate fossil groups, mainly foraminifera and ostracodes, have traditionally been utilized to define and interpret paleoenvironments in the Gulf Coast. In the last decade, studies have demonstrated the value of vertebrates, especially fish otoliths or earstones, in the determination of ancient environmental conditions. This study analyzes the use of fish otoliths and other vertebrate remains in the paleoenvironmental interpretation of the Mint Spring Formation (Vicksburg Group, Oligocene) in Rankin County, Mississippi. The paleoecology of the formation was ascertained based on otoliths and related vertebrate material obtained from three sampled intervals. The vertebrate fossil assemblage included remains from cartilaginous fishes, bony fishes, reptiles, and mammals. The vertebrate- based paleoecology was compared to paleoenvironmental parameters previously developed utilizing various invertebrate groups, mainly foraminifera and bivalves, and to the sedimentological data. The vertebrate-based interpretations agreed quite well with the invertebrate- based data for the formation and provided further evidence of the usefulness of vertebrate-based paleoecology in the Gulf Coast. The fish otoliths provided more detailed data about the paleoecology than the remains of the other vertebrate groups. Although the vertebrate remains proved to be valuable and accurate in the interpretation of the paleoenvironment, limitations on their utilization were noted.

AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana